2,263 research outputs found
WILLINGNESS TO PAY FOR LOCAL COHO SALMON ENHANCEMENT IN COASTAL COMMUNITIES
Salmon restoration and enhancement are dominant environmental policy issues in Oregon and Washington. In response to salmon species listings under the Endangered Species Act, salmon protection and recovery actions are being implemented throughout the Pacific Northwest at substantial opportunity costs. In this paper, we examine the willingness to pay (WTP) of coastal residents for local coho salmon enhancement programs. A contingent valuation study is completed using survey responses from five rural, coastal communities of Oregon and Washington, where coho salmon are prevalent. Our empirical results indicate that coastal residents are willing to pay for local coho salmon enhancement and that WTP varies considerably with individual opinions of the merit of the enhancement program.Resource /Energy Economics and Policy,
Pacific bonito management information document
Management of Pacific bonito in California is examined in this Management Information Document by a State-Federal team of scientists.
Abundance of Pacific bonito in southern California has fallen dramatically between the 1963-1969 period and the 1974-1977 period. Since 1976 the commercia1 fleet has found few large fish in southern California, and has caught fish in the size range of 15 to 57 cm (1.2 to 4.7 pounds). This fact, coupled with the low abundance indices, point out the need for a more active management regime.
To develop management measures for the California bonito
fishery both a surplus yield analysis and a yield-per-recruit analysis were performed. A maximum sustained yield of 10,000 short tons was estimated for the fishery in southern California, while the whole fishery, including Baja California, has an estimated MSY of 13,000 tons. In order to achieve this level of catch, however, the stock abundance must be increased by a factor of five.
Yield-per-recruit considerations suggest that a minimum
size limit in the commercial fishery has two important effects. A three-pound size limit could result in a slight increase in yield-per-recruit. If the size limit is increased to 5 or 7.5 lbs, the yield-per-recruit would fall significantly. Offsetting the effect on yield-per-recruit, however, would be a substantial increase in average amount of spawning per recruit which should result in a proportional increase in recruitment. With the current depressed stock abundance both a reduced annual take and
a minimum size limit on commercial catch would confer
substantial benefits in the form of an increase in the future stock size.
After considering seven different types of management
measures, the team finds that three types -- an annual commercial catch quota, a commercial size limit, and a recreational bag limit -- appear desirable.
Re-establishment of the stock in southern California was
the major consideration in this evaluation because the stock is currently depressed. All segments of the fishery will benefit from a more abundant resource. The difficult issues for policy, however, concern the rate of rebuilding, the degree of risk that is acceptable, and the distribution of benefits among user groups. By judicious choice among the options discussed here, a variety of positions can be established with respect to these issues. The greater the
size limit, for instance, the more benefit is provided the
recreational sector while difficulties are imposed upon commercial fishermen. The higher the quotas adopted, the
slower the stock rebuilding and the greater the risk of continued stock depletion. A final reconciliation of the management options involves social, political and legal considerations which must be thoroughly incorporated by decision-makers before adoption of a management plan. (93pp.
On right conjugacy closed loops of twice prime order
The right conjugacy closed loops of order 2p, where p is an odd prime, are
classified up to isomorphism.Comment: Clarified definitions, added some remarks and a tabl
The waterlogging of floating objects.
We consider the dynamical processes by which a dense, porous object floating in a\ud
body of liquid becomes waterlogged and sinks. We first generalize the classic model\ud
of capillary rise in a porous medium to present an analytically tractable model of the\ud
process, which is valid for objects that are very shallow compared to their horizontal\ud
extent. We find an analytical expression for the time taken for the object to sink under\ud
this approximation. We use a series of boundary integral simulations to show that\ud
decreasing the horizontal extent of the object decreases the time taken to sink. We\ud
find that the results of these numerical simulations are in good quantitative agreement\ud
with a series of laboratory experiments. Finally, we discuss the implications of our\ud
work for pumice fragments, often found floating in open water after a volcanic\ud
eruption, occasionally even supporting plant, animal and human remains
Liquid rocket engine axial-flow turbopumps
The axial pump is considered in terms of the total turbopump assembly. Stage hydrodynamic design, pump rotor assembly, pump materials for liquid hydrogen applications, and safety factors as utilized in state of the art pumps are among the topics discussed. Axial pump applications are included
Simply connected projective manifolds in characteristic have no nontrivial stratified bundles
We show that simply connected projective manifolds in characteristic
have no nontrivial stratified bundles. This gives a positive answer to a
conjecture by D. Gieseker. The proof uses Hrushovski's theorem on periodic
points.Comment: 16 pages. Revised version contains a more general theorem on torsion
points on moduli, together with an illustration in rank 2 due to M. Raynaud.
Reference added. Last version has some typos corrected. Appears in
Invent.math
Leakage from gravity currents in a porous medium. Part 2. A line sink
We consider the propagation of a buoyancy-driven gravity current in a porous medium bounded by a horizontal, impermeable boundary. The current is fed by a constant flux injected at a point and leaks through a line sink at a distance from the injection point. This is an idealized model of how a fault in a cap rock might compromise the geological sequestration of carbon dioxide. The temporal evolution of the efficiency of storage, defined as the instantaneous ratio of the rate at which fluid is stored without leaking to the rate at which it is injected, is of particular interest. We show that the ‘efficiency of storage’ decays like t−2/5 for times t that are long compared with the time taken for the current to reach the fault. This algebraic decay is in contrast to the case of leakage through a circular sink (Neufeld et al., J. Fluid Mech., vol. 2010) where the efficiency of storage decays more slowly like 1/lnt. The implications of the predicted decay in the efficiency of storage are discussed in the context of geological sequestration of carbon dioxide. Using parameter values typical of the demonstration project at Sleipner, Norway, we show that the efficiency of storage should remain greater than 90% on a time scale of millennia, provided that there are no significant faults in the cap rock within about 12km of the injection site
An efficient quantum algorithm for the hidden subgroup problem in extraspecial groups
Extraspecial groups form a remarkable subclass of p-groups. They are also
present in quantum information theory, in particular in quantum error
correction. We give here a polynomial time quantum algorithm for finding hidden
subgroups in extraspecial groups. Our approach is quite different from the
recent algorithms presented in [17] and [2] for the Heisenberg group, the
extraspecial p-group of size p3 and exponent p. Exploiting certain nice
automorphisms of the extraspecial groups we define specific group actions which
are used to reduce the problem to hidden subgroup instances in abelian groups
that can be dealt with directly.Comment: 10 page
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